In this study we evaluate the benthic fluxes of silicic acid along the West Antarctic Peninsula (WAP). Silicic acid (DSi) is one of the macronutrients essential in fuelling biological hot spots of diatom‐dominated primary production along the WAP. Here we measure the concentration and stable silicon isotopic composition of DSi in porewater profiles, biogenic silica content (BSi), and diatom abundance from sediment cores collected along the WAP. We couple these measurements with reaction‐transport modeling, to assess the DSi flux and the processes that release this key nutrient from the sediment into the overlying waters. Our results show that the benthic DSi flux is dominated by the diffusive flux, which is estimated to be equivalent to 26.7 ± 2.7 Gmol yr⁻¹ for the WAP continental shelf. The DSi isotope profiles reveal the important impact of sedimentary processes on porewater DSi and suggest that biogenic silica dissolution is the main source of DSi in porewaters and consequently of the benthic fluxes. Our integrated data‐model assessment highlights the impact of surface productivity on sedimentary processes and the dynamic environment of core‐top sediments where dissolution and reverse weathering reactions control DSi exchanges.

中文翻译：

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硅同位素揭示的南极半岛西部生产热点中的沉积营养物供应

在这项研究中，我们评估了沿西南极半岛（WAP）的硅酸底栖通量。硅酸（DSi）是在WAP上为硅藻为主的初级生产生物热点提供燃料所必需的大量营养素之一。在这里，我们测量了孔隙水剖面中DSi的浓度和稳定的硅同位素组成，生物硅含量（BSi）以及沿WAP收集的沉积物核心中的硅藻丰度。我们将这些测量结果与反应运输模型结合起来，以评估DSi通量以及将这种关键营养物从沉积物中释放到上覆水域的过程。我们的结果表明，底栖DSi通量主要由扩散通量控制，估计相当于26.7  ±  2.7 Gmol yr ^-1WAP大陆架。DSi同位素剖面揭示了沉积过程对孔隙水DSi的重要影响，并表明生物成因二氧化硅的溶解是孔隙水中DSi的主要来源，因此也是底流的主要来源。我们的综合数据模型评估突出显示了地表生产力对沉积过程和岩心顶部沉积物动态环境的影响，在这些环境中溶解和逆向风化反应控制着DSi交换。